1. Field of the Invention
The present invention relates to metal-to-metal antifuse technology. More particularly, the present invention relates to a metal-to-metal antifuse having an improved radiation single event dielectric rupture (SEDR).
2. The Prior Art
Metal-to-metal antifuses are well known in the art. These devices are usually formed between two metal interconnect layers in an integrated circuit and comprises a layer of antifuse material, usually amorphous silicon or an alloy thereof sandwiched between a pair of lower and upper conductive electrodes, each electrode in electrical contact with one of the two metal interconnect layers.
Metal-to-metal antifuses are susceptible to SEDR. A high-energy ion striking the antifuse can set up momentary conduction path in the antifuse material, which can, under certain circumstances, cause the antifuse to become inadvertently programmed. This inadvertent programming phenomenon presents a reliability issue for antifuse-based products intended for use in environments, such as space applications, where radiation is expected to be encountered.
A metal-to-metal antifuse according to the present invention is disposed between a lower conductive electrode and an upper conductive electrode. The conductive electrodes may comprise either a barrier metal or a tungsten plug, and are each in electrical contact with a metal layer, usually a metal interconnect layer in an integrated circuit. An antifuse material is disposed between the lower and upper conductive electrodes and comprises a layer of amorphous silicon. The antifuse layer is sandwiched between two layers of silicon nitride.
A method for fabricating a metal-to-metal antifuse according to the present invention comprises forming a lower conductive electrode, forming a first layer of silicon nitride, forming an antifuse layer, forming a second layer of silicon nitride, and forming an upper conductive electrode.